This invention relates to branched polyphenylene-polyphenylene sulfide blends and composites made therefrom.
There is a need for polymeric compositions which can withstand high temperatures (above 600.degree. F.) for long periods of time and maintain good mechanical properties. One material which has been disclosed as having good high temperature properties is branched polyphenylene. These polymers are composed essentially of carbon and hydrogen in aromatic ring structures, with the rings chemically linked to each other through ortho, meta and para positions. Such polymers clearly are distinguishable from other chemically similar phenylene-type structures, such as polyphenylene oxide, polyphenylene sulfide, polyphenylene sulfone and other polymers containing the designation "phenylene".
Ordinary polyphenylenes generally have been produced by techniques such as acid catalyzed oxidative coupling of the benzene ring in various aromatic compounds and such polyphenylenes possess some degree of high temperature thermal stability, but they are generally linear (parapolyphenylene) polymers which are relatively insoluble and infusible. Polyphenylenes have been produced which do possess certain limited solubility, but these have generally been at number average molecular weights of only about 1000 to 2000. Generally, these low molecular weight polyphenylenes contain only a low degree of branching, that is, they are still relatively linear polymers which contain long linear segments.
The branched polyphenylenes useful in producing superior blends of this invention are those novel polyphenylenes disclosed by Wennerberg and Wang in U.S. Pat. No. 3,792,099 and produced by the process described in U.S. Pat. Nos. 260,670 3,829,518 and 3,798,281, all of these patents incorporated by reference herein. These polyphenylenes possess increased solubility over prior art polyphenylenes and excellent thermal stability over a number average molecular weight range from 1000 to over 10,000.
Polyphenylene sulfides are crystalline polymers formed from polyhalo aromatics and alkali metal sulfides.
Although branched polyphenylene and polyphenylene sulfide have reasonable high temperature properties neither is adequate for applications such as in air craft bushings or electronic printed circuit boards where good mechanical properties and service temperature above 600.degree. F. are required.